Investigation into the seismoacoustic properties of specific polycrystalline materials used in nuclear reactors

Abstract

The characteristics of the wave fields observed during the transmission of quasi-longitudinal ultrasonic waves through polycrystalline graphite samples have been studied. The specific features of propagation of elastic waves in a bilayer medium, where one of the layers (isotropic) is an acrylic glass hemisphere and the other (anisotropic) is a polycrystalline porous graphite hemisphere, are considered. The velocities and propagation times of quasi-longitudinal waves in polycrystalline graphite samples and a bilayer acrylic glass-graphite sample in different directions are experimentally measured by ultrasonic spatial sounding. The experimental results are compared with theoretical calculations using the data on graphite crystallographic texture obtained previously by neutron diffraction. The reasons for the discrepancy between the theoretical and experimental characteristics of elastic waves in the media under study are established and analyzed.